Superconducting gamma-detectors for non-destructive analysis in nuclear safeguards

Abstract

Ultra-high energy resolution superconducting gamma ray detectors operated at temperatures of 0. 1 K can improve the accuracy of non-destructive analysis of nuclear materials. These detectors offer an order of magnitude improvement in resolution over conventional high-purity germanium detectors. The increase in resolution improves the peak-to-background ratio, and reduces errors from line overlap, therefore allowing the identification of weak gamma rays on top of a high Compton background. The higher resolution also improves the accuracy of isotope ratio measurements in fissile material. In order to understand the spectral background and improve the detector sensitivity, GEANT4 Monte Carlo simulations are used to model the low energy response of these superconducting detectors. The models are used to identify the spectral contributions from Compton scattering and from the detector shielding to assess the feasibility of identifying fissile material in spent nuclear fuel. The detector simulations are compared for accuracy to experimental data. We discuss the superconducting detector model, possible improvements in spectrometer configuration, and their use in nuclear safeguards by the IAEA.